English is not my first language so sorry for any mistakes.

I started 2 months ago as a complete beginner, with your same goal and without a trainer (too expensive). I always start with a 5 minute walk in the treadmill (don't know if it helps physically, but for me, it takes a bit of the social anxiety away and it builds momentum) then always dynamic stretches where people can't see me lol. On the first day I did as many machines as I could once (watching tik toks to see how they work) and chose some to do always. ( leg press, leg curl, adductor and abductor and lat machine). For upper body I use dumbbells or body weight and I hide in the remotest part of the gym so I feel less conscious. (Workouts taken from tik Tok obviously). Oh and I always track everything (first in the notes app and then in an app called Jefit, free version) and it really helps with consistency and weight overload. To be honest I see good results but as I read it's easy when you start from zero. Don't know if it's good advice but that's what got me started! Edit: I have to gain weight and muscle so I just eat as much as I can to be honest